Small fragments of plastic waste are damaging the health of lugworms, putting a key cog in marine ecosystems at risk. Published in Current Biology, a new study by scientists at the University of Exeter and the University of Plymouth shows the impact of microplastics on the marine worms’ health and behavior. By exposing specimens to contaminated sediment in a laboratory, the researchers were able to observe a 50 percent reduction in energy reserves and other signs of physical harm.

According to the study, the lugworms feed less and breed less in areas heavily contaminated by microplastics and the harmful chemicals used to manufacture them. These include plasticizers, dyes and antimicrobials which, when discarded into the ocean, may also harm a multitude of sea creatures both large and small.

Microscopic fragments of plastic — or microplastics — are pieces of plastic less than 5 mm in diameter and are a global marine pollutant. This image shows microplastic fragments and pre-production pellets collected from a sandy shoreline in Europe; these items are continually fragmenting in the environment. Current Biology, Wright et al.

When plastic litter breaks down into pieces smaller than five millimeters in diameter, it becomes known as microplastics. Such microplastics have spread across the planet and researchers have only begun to discover the extent to which they are affecting marine wildlife. Small animals regularly mistake microplastics for food. Because plastic takes up room in their digestive systems without providing any nutrition, the animals that consume it are at risk of illness, malnourishment and starvation. Given that it is estimated that plastic makes up to 60-80 percent of all ocean debris, the impact on ecosystems could become a formidable challenge for environmentalists across the globe.

Lugworms are an important food source for many marine species, and play a pivotal role in maintaining sediment quality. Because of their foundational position, reductions in lugworms would likely be echoed by impacts on many ocean communities.

Microplastics. Credit: Current Biology, Wright et al.

“They are the earthworms of the sea; they keep the sediment healthy for other animals and microorganisms to thrive in,” says Tamara Galloway of the University of Exeter and co-author of the report. “These effects could cause populations to decline with knock-on effects for predators. Reduced feeding also means the sediment is being re-worked less. The condition of the sediment could fall, leading to a decline in the communities which live in it.”

The findings of this study could represent an ominous precedent, as it is likely that many other small animals are being impacted in similar ways with similar ecological consequences.

“There are many other species which adopt a similar feeding behavior to lugworms, such as some sea stars, sea cucumbers, fiddler crabs and other marine worms, all of which could be at risk of ingesting microplastics and the chemical burden they might carry. These animals tend to play important roles at the base of marine food webs,” warns Galloway.

While it is very difficult to retrieve plastic waste from the world’s oceans, Galloway is convinced that it isn’t too late to make a serious difference, telling mongabay.com “if we tightened up our waste management practices and stopped throwing away so much plastic waste, we wouldn’t have this problem.”